Going Away? Make Sure Your Electric Car Stays Happy Without You

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2011 Nissan Leaf: One Year Drive Report

2011 Nissan Leaf: One Year Drive Report

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Electric cars, just like every other device or machine that relies on rechargeable batteries, slowly discharge over time. Leave them in low state of charge for too long, and their traction battery packs are destroyed.

Which is why automakers like Nissan and Chevrolet recommend owners follow specific instructions before leaving their Nissan Leaf and Chevy Volt cars for extended periods of time.

As we’ve proven, a 2011 Nissan Leaf will lose a few miles of charge if left unplugged in a semi-charged state for 8 days

Leaving your car plugged into a suitable charging station while you’re away might seem like a sensible solution, especially if you time charging to finish just as you return. 

There are two batteries

But as some Nissan Leaf owners over at MyNissanLeaf.com have discovered, leaving your Leaf plugged in while away could drain the car’s other battery -- the one that runs its 12-volt accessory circuits. 

Returning to their cars after a vacation or time away, these owners are reporting that their Leafs are unresponsive and often won’t unlock. 

2011 Nissan Leaf SL

2011 Nissan Leaf SL

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Just like almost every other car on sale in the U.S. today, cars like the 2012 Chevy Volt and 2012 Nissan Leaf have 12-volt accessory batteries that provide power to run onboard computers, entertainment systems, lights and wipers. 

In a gasoline car, its 12-volt battery is kept charged by an alternator, powered by the car’s engine. In an electric car, a high-power dc-to-dc converter keeps the battery fully charged, fed by power from its traction battery pack. 

It’s complicated...

In a car like the Nissan Leaf, its 12-volt battery will gradually discharge as it provides power to always-on systems like the alarm, locking system, radio and telematics computers. 

When it gets too low and the car is unplugged, the Leaf’s 12-volt solar panel or dc-to-dc converter kicks in to charge it back up. 

If the Leaf is plugged into a charging station and drawing power to charge its on-board traction battery pack, it should also charge up the 12-volt battery.

But when plugged into a charging station that is not actively charging the car, the Leaf enters into an operational mode that continuously looks to communicate with the charging station, drawing power as needed from its 12-volt accessory battery.

In this mode, the extra power drain can flatten the 12-volt battery -- not the traction battery -- in under a week.

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Comments (8)
  1. Great report.

    This is more than a little disappointing and seems like something Nissan needs to find a solution to.

  2. Wow, the complete opposite of Tesla's recomendation to always leave the car tethered to an outlet!

    It seems like manufacturers will need to issue instruction cards for each model to spell this out… I guess this is what we mean when we say that Nissan rushed out the Leaf but, I don't mean that in a bad way - I think this is an eye-opener for all the manufacturers and a reminder that buying an EV can be an adventure… One where someone has spilt coffee on the map and no one even knows the proper spelling of the destination but, hey, it's a really nice day for a drive.

  3. And what an adventure!

  4. Michael, don't you mean a "live" outlet? She is talking about plugging into a charging station that is on a timer and is off for extended periods.

    Besides, the Tesla does not have a 12 volt battery, does it?

    Of course on the Think I can just leave a trickle charger connected to the 12 volt accessory outlet (cigarette lighter outlet) which is always connected to the 12 volt battery even when the car is off. Most Japanese cars switch off the outlet so you cannot do this.

  5. Jim,

    Actually, the Roadster 2.x does have a 12v battery. It's a motorcycle sized one mounted up front.

  6. The Chevy Volt has the exact same problem. The owners manual instructs you to disconnect the 12V negative terminal. This is also a common suggestion for gas cars.

    Keeping you car plugged in for long periods of time on a public charger is bad public charging etiquette. California even has laws regarding this.

  7. The Prius and other vehicles also have this problem. Namely cars equipped with a smart key system. They advise you to push a button under the steering wheel on the bottom of the dash to disable the system if you're planning on leaving the car for an extended period.

  8. Can't see a problem here since I recently left my Leaf outside in winter for six weeks unplugged while abroad. I monitored it via carwings several times and it showed no drop at all.
    Upon my return it was exactly as I left it with 80% charge.

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